The CAT1021, CAT1022 and CAT1023 are complete memory and supervisory solutions for microcontroller-based systems. A 2k-bit serial EEPROM memory and a system power supervisor with brown-out protection are integrated together in low power CMOS technology. Memory interface is via a 400kHz I2C bus. The CAT1021 and CAT1023 provide a precision VCC sense circuit and two open drain outputs: one (RESET) drives high and the other (RESET) drives low whenever VCC falls below the reset threshold voltage. The CAT1022 has only a RESET output and does not have a Write Protect input. The CAT1021 also has a Write Protect input (WP). Write operations are disabled if WP is connected to a logic high. All supervisors have a 1.6 second watchdog timer circuit that resets a system to a known state if software or a hardware glitch halts or “hangs” the system. For the CAT1021 and CAT1022, the watchdog timer monitors the SDA signal. The CAT1023 has a separate watchdog timer interrupt input pin, WDI. CAT1021, CAT1022, CAT1023 Supervisory Circuits with I2C Serial 2k-bit CMOS EEPROM, Manual Reset and Watchdog Timer FEATURES ■ Precision power supply voltage monitor — 5V, 3.3V and 3V systems — Five threshold voltage options ■ Watchdog timer ■ Active high or low reset — Valid reset guaranteed at VCC = 1 V ■ 400kHz I2C bus ■ 3.0V to 5.5V operation ■ Low power CMOS technology ■ 16-Byte page write buffer ■ Built-in inadvertent write protection — WP pin (CAT1021) ■ 1,000,000 Program/Erase cycles ■ Ma
The CAT1021, CAT1022, and CAT1023 are supervisory circuits that combine a 2 k‑bit serial EEPROM with a power‑monitor and reset controller. They provide precision voltage monitoring for 3 V, 3.3 V and 5 V systems, optional write‑protect, and a 1.6 s watchdog timer to reset a microcontroller when activity stops.
The document lists pin descriptions, package options (8‑pin DIP, SOIC, TSSOP, TDFN, MSOP), electrical limits, AC and DC characteristics, reliability data, and ordering information. It also includes revision history and legal notices for Catalyst Semiconductor products.
| Supply voltage systems | 5 V, 3.3 V, 3 V |
|---|---|
| EEPROM endurance | 1,000,000 program/erase cycles |
| Data retention | 100 years |
| Watchdog timer timeout | 1.6 seconds |
| EEPROM size | 2 k‑bit |
| Operating temperature (industrial) | -40 °C to 85 °C |
| Operating temperature (extended) | -40 °C to 125 °C |
| TDFN package height | 0.8 mm max |
The watchdog timer triggers a reset after a timeout of 1.6 seconds of inactivity.
The EEPROM is rated for 1,000,000 program/erase cycles.